STS-73 Day 14 Highlights

Columbia, with both payload bay doors fully open, currently is in
its third thermal conditioning session designed to warm the underside
of the orbiter. It will remain in the "belly to sun" attitude until
about 2 p.m. Thursday afternoon.

"Things are going fantastically well, and we're just looking forward
to getting as much science in the remaining time as we can," explained
USML-2 Alternate Payload Specialist Glynn Holt early this morning in
an interview for Mutual NBC Radio as fluid physics and combustion
science took center stage on the thirteenth night of the second United
States Microgravity Laboratory mission.

Spacelab systems and facilities continued to operate well and
gather good data. The crew worked with the Fiber Supported Droplet
Combustion experiment in the Glovebox, performed the fission
experiment in the Drop Physics Module, monitored fluid flows for the
Geophysical Fluid Flow Cell experiment, and initiated the last run of
the Supression of Transient Acceleration by Levitation Evaluation
(STABLE) vibration isolation system.

"Fred gets an A+ in combustion theory," exclaimed investigators for
the Fiber Supported Droplet Combustion experiment (FSDC), offering
Payload Specialist Fred Leslie "a collective high-five" for his
"outstanding work" in the Glovebox facility. Leslie had been placing
drops of fuel on a thin fiber, using needles in the experiment module,
and igniting them with a hot wire. Earlier in the evening, Leslie
worked closely with the FSDC science team to successfully troubleshoot
difficulties with clogged drop accumulators, and then performed a
series of excellent burns, varying the quantities of methanol and
methanol/water fuel with each run. Also varied were fiber size and
air flow rates. These experiments resulted in some droplet extinction
diameters (the size of the drop as it burns out) larger than any
initial droplet size capable of being studied on Earth. The science
team was very pleased with what they described as the "textbook
quality" data received and expressed their appreciation for the crew's
hard work and persistence. Leslie showed his enthusiasm for the work
when he humorously responded, "I don't get to play with fire much up
here. I'm kind of enjoying it."

The NASA Lewis Center's FSDC investigation consists of new hardware
and is on its first flight. The primary objective for this research
is to provide scientists new fundamental insights into the dynamics of
droplet burning which will be compared to state of the art analytic
and numerical models.

"It did fission, and I got some good data," announced Mission
Specialist Cady Coleman referring to the initial drop fissioning runs
in the Drop Physics Module. Coleman used sound waves to manipulate
rotating drops of silicone oil until they split, or underwent fission.
Project Scientist Arvid Croonquist and his science team worked with
Coleman throughout the night, uplinking instructions and watching
downlink video. They were testing one set of theories that describes
the breaking apart of distorted, or pre-flattened, drops while varying
the viscosity (or thickness) of the fluid.

Drop Dynamics Experiment Principal Investigator Taylor Wang and his
co-investigators from Vanderbilt University observed and analyzed
conditions at which drops of various sizes and viscosities split, and
he described Coleman's first run of the procedure as "a very
successful drop fission." Also, during this run, the science team was
able to get good pictures of the ligament, or thread of fluid,
connecting the two halves of the drop as it passed through its
critical "saddle" point while splitting in two.

On the first USML mission, Wang's team used the Drop Physics Module
to confirm a theory that was more than 100 years old. Using fluids
ranging from water to oils, the module spun single drops until they
formed a dog-bone, or two lobe shape. All the drops changed into the
same shape at the same point and at exactly the point that had been
predicted over a century ago by fluid dynamics pioneer Lord Raleigh.
Results from USML-2 are helping to develop theoretical models for the
drop fission process.

Troubleshooting continues on the High Data Rate Recorder (HDRR),
which began experiencing intermittent data degradation between MET
12/14:30 and 12/14:58. Scientific data is being stored on the
Orbiter's recorder during loss of signal periods and downlinked via
Hi-Pac TV.

The Space Acceleration Measurement System (SAMS) and the
Orbital Acceleration Research Experiment (OARE) continued to track
accelerations caused by movements and variations within the Shuttle,
as well as by Shuttle maneuvers and atmospheric drag. The Principal
Investigator Microgravity Services Project team, of NASA's Lewis
Research Center, is at the SpacelabMission Operations Control Center
to help scientists evaluate the effects of accelerations on sensitive
microgravity experiments. Both instruments make continuous records of
accelerations for analysis after the flight. In addition, OARE is
providing data on the relatively steady, or low-frequency,
accelerations that occur in the Shuttle. This information is being
provided to the USML-2 Principal Investigators in real-time throughout
the mission.

The crew also activated the STABLE instrument, and unattended
monitoring continued during the final run of the device. The STABLE
system was developed by NASA's Marshall Space Flight Center jointly
with McDonnell Douglas to test a device designed to isolate small
science experiments from high-frequency accelerations, including
Shuttle maneuver operations and crew activity.

What flight controllers believe to be an occasional glitch with two
of Columbia's small steering jets reoccurred today, resulting in a
temporary shutdown of the two small, or vernier, jets located on the
tail of the spacecraft. The glitch has occurred twice before during
the mission, and has been resolved each time by turning the shuttle's
autopilot off and on. The same actions restored the jets function
during this afternoon's problem, and they are now functioning
normally. The glitch poses no problem for the mission, since
Columbia's 38 primary jets are all in good working order. The small
vernier jets are only used to minimize interference with sensitive
experiments ongoing in the lab module.

The four crew members on the Red Team handed over to the Blue Team
at 2:38 p.m. CST. The three Blue Team crew members will be on duty
till 2:38 a.m. Friday when they hand over to the Red Team. Early in
the afternoon Pilot Kent Rominger, and payload specialists Kathryn
Thornton and Al Sacco conducted experiments in space and answered
questions from students in Worcester, Massachusetts, and Louisville,
Kentucky. The experiments and questions focused on surface tension
and combustion concepts. Students were involved in ground based
adaptation experiments that have enabled them to work alongside their
counterparts in space.

To demonstrate surface tension in space, Sacco squeezed out a ball
of orange juice which immediately formed a sphere. The demonstration
was designed to illustrate how surface tension can make a fluid form a
sphere when it doesn't have to contend with gravity. Shortly after the
demonstration, Sacco drank the experimental orange juice sphere.

The surface tension experiment studies the transition between steady
fluid flows to unstable fluid flows. Scientists are interested in such
studies because of their applications in areas of materials processing
such as the production of high-tech crystals, metals, alloys and
ceramics. The combustion experiments will give scientists insight into
the dynamics of burning fuel.

After completing its third thermal conditioning period earlier
today, Columbia returned to a "gravity gradient" attitude with the
orbiter tail pointing towards the Earth and the port wing pointing in
the direction of travel. Because the gravity gradient attitude shades
portions of the orbiter, thermal conditioning periods are needed to
warm the underside of the orbiter and subsequently increase the
landing gear tire pressure. One more warm-up period is expected on
Friday morning.

As the past 12 hours unfolded on the second United States
Microgravity Laboratory mission, Payload Commander Kathryn Thornton
and Payload Specialist Al Sacco spent a good portion of their shift
working on experiments in the Glovebox facility.

Investigators for the Fiber Supported Droplet Combustion Glovebox
experiment saw something this morning they hadn't expected.
Hydrocarbon-mix droplets deployed in the facility burned slower and
produced more soot than drops of an alcohol-mix. Researchers also
learned that larger drops burned longer, as expected. These tests,
which study combustion behavior in microgravity, were conducted using
various fuel mixtures in different-sized drops and changing air flow
rates to see how quickly the drops ignite and extinguish. Throughout
the morning, Thornton deployed the drops onto thin fibers, and ignited
them by placing an electrical hot wire near the drop. The longest
burn, that of a large hydrocarbon-mixed drop, lasted for about 40
seconds.

Scientists will analyze their data post-mission to learn more about
the chemistry of the combustion process, information which will aid in
the development of combustion experiments for the International Space
Station. Research in this field could spark a totally new approach in
the design of space- based safety equipment, such as fire alarms. It
could also aid in cleaner fuel use on Earth.

The first crystal growth experiment ever designed to produce a
crystal without the growing portion touching its container wall has
been completed in the Crystal Growth Furnace. Principal Investigator
Dr. David Larson hopes to bring home an almost defect-free cadmium
zinc telluride crystal thanks to the unique container apparatus,
designed to grow the crystal as a liquid bridge. The two-inch (five
centimeter) crystal, which grew for about 30 hours, is the sixth of
eight semiconductor crystal growths planned for the versatile,
high-temperature furnace. Growing these semiconductors in
microgravity is necessary for a more uniform distribution of chemicals
in order to obtain crystals with a more perfect structure. Cadmium
zinc telluride crystals are used to make infrared detectors.

The next sample set for processing in the Crystal Growth Furnace is
a crystal of gallium doped germanium. Growing this material, which
has well-known properties, provides an engineering test of a new
Crystal Growth Furnace capability to mark the boundary between the
melted and solidified portions of a crystal at given time intervals.
The marks make post-flight analysis of crystal growth more precise.

Today's experiment runs of the Particle Dispersion Experiment
increased Principal Investigator Dr. John Marshall's data base for
future Shuttle and International Space Station aerosol dispersion
investigations. Performed in the Glovebox facility, the experiment
demonstrates how fine natural particles, such as dust, disperse within
an atmosphere, then assemble back together (or reaggregate) into
larger clusters. Earlier this week the experiment confirmed a theory
that aggregation occurs in all dust clouds.

Investigators for the Geophysical Fluid Flow Cell Experiment today
set their experiment parameters to create flows mimicking those of the
sun's interior. Information from this experiment run will be used to
validate data collected earlier in the mission on this same phenomena.
Rotation rate, temperature and voltage within the facility are varied
to simulate specific atmospheric conditions. The fluid flows that
result are relevant to the study of oceans, planetary atmospheres, and
stars Ð- information could one day aid in weather forecasting.

Protein crystals activated earlier in the mission continue to grow,
ensuring investigators that there will be ample data for post-mission
analysis. One of these experiments, the Protein Crystallization
Apparatus for Microgravity, holds more than six times as many samples
as are normally accommodated in the same amount of space. These
crystals are being grown using the vapor diffusion method. In vapor
diffusion, liquid evaporates from a protein solution and is absorbed
by a reservoir solution in a wicking material. As the protein
concentration rises, the proteins form crystals.

These experiments are a precursor to long-duration crystallization
investigations aboard the International Space Station, which would
greatly benefit from the ability to control crystal growth times of up
to approximately six months in length. Proteins play important roles
in daily life, from providing nourishment to fighting disease.

When the blue shift comes on duty, Mission Specialist
Catherine Coleman and Payload Specialist Fred Leslie will
devote the majority of their time to Drop Physics Module and
Glovebox experiments.